HEART RHYTHM OBSERVED DURING POSITIVE HEAD-UP TILT TEST
Introduction: Heart rhythm obtained during provocative condition can be used to guide therapy in vaso-vagal syncope (VVS).
The aim of this study was to analyze the heart rhythm during positive head-up tilt test (HUT).
Methods: Thirty-two consecutive VVS patients (age 48,4, 50% women) presenting with 1 syncope performed HUT in our cardiology department. The patients were tilted at 70 degrees. If the test was negative in the passive phase (20 to 40 minutes) it was potentiated by the administration of 300 micrograms of sublingual nitroglycerine. Occurrence of VVS and hemodynamic response during passive and nitroglycerine phases were evaluated. The heart rate, arterial blood pressure and 12-leads ECG were recorded during syncope or presyncope.
Results: Eighty-one percent (26/32) presented a positive test. Major types of arrhythmia were sinus bradycardia, junctional escape rhythm and sinus arrest. Thirty-one percent (8/26) of patients presented sinus arrest (asystole more then 4,5 seconds), 19,2 % (5/26) presented junctional rhythm, 19,2 % (5/26) presented sinus bradycardia and 15,38 % (4/26) presented sinus tachycardia (with fall in the systolic blood pressure <60mmHg). In the remaining patients: 15,38 % (4/26) the cardiac rhythm was normal sinus rhythm (60-90/min). Eighty percent of the patients with sinus arrest presented asystole during active phase and only 20% during the passive phase. The shortest period of asystole was 4,6 seconds and the longest 19 seconds (in this case a double chamber pacemaker was implanted). ECG and the complex was narrow with a frequency of 35-45/min.
Conclusions: The common types of arrhythmia observed during positive NUT were sinus bradycardia, junctional escape rhythm and sinus arrest. Patients with sinus arrest > 9 seconds were implanted.